Piglets are 3.5 - 4.5 pounds at birth. Pigs are the fastest growing animal on the farm. They grow 2-3 lbs. a day.
Piglets establish a "teat order" within 3 days of birth. Since the front teats have more milk your stronger piglets will be found there. Your smaller, weaker piglets will be toward the rear. In the video you see them in the early stages of determining this order. The piglet at the rear was JUST born and is still finding her way around. If you look closely you'll see she still has birthing fluid on her.